It is conventional to use filters and separators for removing foreign objects, and condensing and removing water and other condensable liquids, from pressurized air lines and the like. Typically, such filters include an air inlet, an air outlet and a filtering element mounted between these elements in the flow path. Such filters also include a reservoir or filter bowl through which the air flow is at least partially passed causing the moisture and other condensate in the air to be collected and condensed on the inside surface of the reservoir or bowl. The force of gravity causes such condensed materials to accumulate at the bottom of the reservoir together with any other foreign objects. Periodically, this accumulated material and liquid must be discharged when the reservoir or filter bowl has become full of material.
Numerous drain systems have been devised for the discharge of the accumulated material. Two such devices are shown in U.S. Pat. No. 3,980,457, issued to J. I. Smith on Sept. 14, 1974, and in U.S. Pat. No. 3,993,090, issued to Paul M. Hankison on Nov. 23, 1976. In the first of these two patents, there are a pair of valves, a pilot valve and a discharge valve. The pilot valve is magnetically operated and includes a float which moves in response to changes in the liquid level within the reservoir to magnetically open and close a fluid valve in response to that liquid level. Opening of the fluid valve may thereafter cause the opening of the second valve for other operations such as the drainage of the reservoir. In the second of the patents, there are also two valves, a pilot valve and a discharge valve. In this device, a float is held in a submerged condition for a time to create a superbuoyancy condition. When a sufficient superbuoyancy condition is achieved, the float suddenly rises to the surface of the liquid causing a snap action of the pilot valve. This opening of the pilot valve then quickly opens the discharge valve for the removal of material contained within the reservoir. In both of these patents, the pressure of the pneumatic system to which the trap is attached is the driving force which opens the discharge valve.
Since the operating valves and the drain valves are located within the reservoir, various disadvantages exist in the devices described in the above-identified patents. For example, the discharge valve or its operator may be damaged by, or may collect, dirt and other abrasive materials during the discharge operation. Also, they may be affected by corrosive action since they are in contact with the collected material. These deleterious conditions affect the future correct operation of the discharge valve. Further, since the discharge valve is located within the reservoir as part thereof, it is a difficult and an expensive procedure to replace components of this discharge valve. Since the pilot valve also is operated by the air pressure of the pneumatic system to which the reservoir is connected, this valve may become contaminated with some of the impurities.
Still other of these known devices for accumulating condensate and impurities from pneumatic systems are described in the background sections of the above-identified patents.
Accordingly, it is an object of the present invention to provide a drain system for a reservoir utilized in the accumulation of condensate, and impurities from pneumatic systems, wherein the discharge valve is located externally to the reservoir to facilitate replacement of components, if necessary.
It is another object of the present invention to provide a discharge valve for the reservoir which incorporates a self-cleaning feature whereby dirt and other such impurities have negligible effect on valve operation and provides for a positive shut-off of every cycle without leaks therefrom.
Another object of the present invention is to provide a pilot or control valve housed in a separate chamber integral with, but separate from, the main reservoir area where collected material is stored whereby the control valve is not affected by pressure, dirt and other contaminants which would cause most pilot valves to fail.
It is still another object of the present invention to utilize a pair of magnets of normally opposite polarity, one in a valve plug and one in a float, that are magnetically coupled such that one of the magnets effectively reverses polarity when the float within a liquid reservoir reaches the uppermost position, thereby providing a snap opening of this valve. These magnets are so positioned that at the lowest level of the float, the magnet is again effectively reversed in polarity causing the rapid closing of the associated valve.
Other objects and advantages of the invention will become apparent upon reading the hereinafter detailed description with reference to the drawings.